Pentadiene polymers as elastomer additives



Patented May 12, 1953 @nieuwe (Gleim-3mi "both natural 'and synthetic 'Tubbers and Ait; 'ls

:known that "Variations 'in ,properties "c'f rxljbe'r products can beprdducedthrough the use "of `different plesticizingagents- Agocplastidizer,

'arc-:mot "desirable to use carcass stocks.v A

zaswell t:is other goo physical'propetiesfis high- 1y desirable. n Y

A'I have 'new iscovere thtpolymers of 1,3- perxtasdienes are ygoed frunber 'plastcizers andgfive 'products with l"inipfroveizl "tack 'aswe'ha's other desirable physical prop'e'ties. The new *plastik -cize1'.s, tacki'ersjor vsoft-,eners -ef 'my invention can very eivan'tageously beused in carcasses wherein synthetic fel-astomers aire use. Theseplasticizers eeniprisepolymers'pwperedfrcm Ineritalienes 'oftheformlila diene, isoprene, pentadienes, etc., or the copolymerization of such diolens with a compound containing a CH2=C group copolymerizable therewith, such as styrene, acrylonitrile, etc. Examples of such rubber-like polymers are p01- ymers ofl butadiene-styrene,. isoprene-styrene, butadiene-acrylonitrile, polybutadiene, etc. The softeners, plasticizers, or tackiers of my invention can be used with butyl rubber stocks Whichare produced by co-polymerizing a major quantity of one or more monoolens, such as visobutylene, with a minor quantity of a conjugated diolefin, such as those mentioned hereinbefore. The softeners, plasticizersyor taekifiers of my invention can be used with reclaimed natural or synthetic rubbers and to various mixtures of natural, synthetic, reclaimed natural and reclaimed synthetic rubber.

The plasticizing or softening agents of this invention are applicable in compounding both natural andgsynthetic rubbers. They are particularly valuable in improving the tack'of low temperature synthetic elastomers, the relatively newly developed butadiene-styrene elastomers produced by emulsion polymerization at temperatures in the range of -20- to 15 C. being improved particularly well. In their preparation the monomers used are usually from 50 Ato 85 weight per cent butadiene. Low-temperature synthetic rubbers in which these pentadiene polymers are incorporated are readily processable and have good physical properties. Similar effects are produced with other elastomers. One of the advantages of these plasticizers is that they are vulcanizable, i. e., they undergo vulcanization along with the rubber and become thoroughly incorporated in the vulcanizate. In this respect they differ from many of the commercial plasticizers which are not vulcanizable and therefore remain as unconverted materials in the finished product. These softeners can be incorporated into the rubber on a mill, in a Banbury mixer, etc., or, if preferred, they can be added to the latex. If they are added to the latex,

it is desirable that they be added as a latex themselves. They can be added tothe rubber before, during or after the addition `of other compounding ingredients.

The amount of pentadiene polymer, or mixture of pentadiene polymers, employed as a plasticizer will vary depending upon the type of rubber stock` being processed and the properties desired in the finished product. It will usually be in the range from 3 to 25 parts by weight per 100 parts by weight elastomer. n 1

Vulcanizable organic elastomer compositions rusually contain fillers; modifiers; softeners', tackiiiers, and plasticizing substances; vulcanizing agents; age resistors or antioxidants ;l and accelerators of vulcanization. The exact composltion of the vulcanizable organic elastomer composi- -tion depends upon the use to which the vulcan- ,izable composition is to be putg. The new softeners, plasticizers or tackiers of, my invention can be used in all of the commonly usedicompounding frecipes.` 1

Carbon black is added to many vulcanizable Lorganic elastomer mixes during compounding as a filler. There are many types of carbon blacks used today in compounding, among which are:

blacks.

nace carbon blacks (HMB1 blacks); reinforcing furnace blacks (RF blacks) and very fine furnace blacks (VFF blacks) easy, medium, or hard processing channel blacks; lamp blacks; fine and medium thermal carbon blacks; acetylene carbon blacks; semi-reinforcing furnace carbon blacks;

conductive furnace and conductive channel carbon blacks; and high elongation furnace carbon Other pigments or additives, such as ferrie oxide, magnesium carbonate, titanium dioxide, zinc oxide, hydrated alumina, kieselguhr, slate dust, zinc peroxide, zinc chloride, lead peroxide, lead oxide, chlorinated parains, glue, barytes, fossil our, lithopone, various clays, finely divided silica, whiting, etc., can be added as fillers or to modify the properties of the vulcanizable composition or vulcanized composition, such properties as the rate of cure, resistance to scorching during processing, activation of acceleration, etc.

Other softeners, tackifiers and plasticizingsubstances can be used in conjunction with lthe softeners, tackifiers and plasticizing materials of this invention, if desired. There are many such substances, among which are vegetable oils, such as palm oil, rape oil, olive oil, linseed oil, castor bean oil, soya bean oil, tung oil; bitumens including so-called mineral rubbers, which comprise natural products, such as gilsonite, rafaelite, and also high-boiling petroleum residues, asphalts, etc.; pine tar; parafiin wax; mineral oils; fatty acids, such as oleic acid, stearic acid, palmitie acid, lauric acid, etc.; ceresin; naphthalenes; rosin; Wool grease; carnauba wax; the many organic chemical compounds, such as glycerol, glyceryl monostearate, glyceryl monooleate, glyceryl monoricinoleate, trioctyl phosphate, triglycol dioctoate, ethylene glycol monostearate and the mono-oleate, phenol-formaldehyde thermosetting resins, polyalpha-methyl styrene, and other polymers of styrene and substituted styrene, dioctyl phthalate, dioctyl sebacate, polybutenes, zinc resinate, coumarone resins, dihydroabietic acid, etc. Some of these compounds aid tackiness as well as soften or plasticize the vulcanizable organic elastomers. Also, some of them exhibit modifying characteristics.

Vulcanizing agents are added to vulcanize th Yorganic elastomers during the vulcanization step of processing. There are a wide variety of vulcanizing agents, such as: sulfur, including powdered sulfur, or in one or more other forms, and mixtures thereof; so-called plastic sulfurs; sulfur-containing compounds, such as sulfur chloride, hydrogen sulfide, sulfur thiocyanate, tetraalkylthiuram disuldes, etc.; selenium; tellurium; benzoyl peroxide; trinitrobenzene; dinitrobenzene; nitrobenzene; quinones; certain inorganic oxidizing agents;' diazoaminobenzene and its derivatives; other nitrogen-containing compounds, etc. n

Accelerators of vulcanization are added to accelerate vulcanization during the vulcanization step of processing. There are many other known accelerators of vulcanization, such as: thioureas; thiophenols mercaptans; dithiocarbamates; xanthates; trithiocarbamates; dithio acids, mercaptothiazoles; mercaptobenzothiazoles; thiuram suldes;` organic-cobalt chelatesjetc., and various mixtures thereof. Some Widely used and particularly good accelerators are, for instance, mercaptobenzothiazole, benzothiazyl disulfide, diphenylguanidine, zinc salt of mercaptobenzothiazole, zinc benzothiazyl sulfide, tetramethylthiuram disulfied, N-cyclohexyl-2-benzothiazole sulfenamide, aldehyde-ammonias, triphenylguanidine, zinc dibutyl and zinc dimethyl dithiocarbamate, many others, and mixtures thereof.

In most cases it is the usual practice to add age resistors or antioxidants to Avulcanizable organic elastomer mixes during the mixing step of processing in order to slow down orl prevent the deteriorationof the vulcanized product. Antioxidants or age resistors have the property yof maintaining tensile strength, resistance'to abrasion, elasticity, preventing flex cracking, etc. One or more antioxidants are usually employed, such as phenyyl-beta-naphthylamine, p-aminophenol, hydroquinone, p-hydroxydiphenyl, diphenylamine2,4 toluene diamine, p-ditolylamine, o-ditolylamine, beta-naphthyl-nitrosoamine, N,Ndiphenyl diaminoethane, phenyl alpha naphthylamine, p,p-diaminodiphenylmethaney etc.

The vulcanizable organic elastomercompositions resulting from admixing the various ingredients with the new softeners, plasticizers and/or tackiers of my invention by the methods known in the prior art, are vulcanized in the usual manner after they are molded or shaped into the desired shape by the numerous shaping operations of the prior art, such as calendering, casting from solution, continuous or discontinuous extrusion, molding in open or closed molds, etc., and they can be used for the many purposes for which other similar compositions are used. For example, they can be used for tire tubes, tire treads, tire casings, shoe soles and heels, raincoats, table covers, hose for the transmission of fluids, belts, balloon coverings, printers rolls, printers blankets, engraving plates, aprons, gloves, masks, tanks, battery cases, friction tape mats, wire insulation, etc. Fabrics can be coated or impregnated by calendering or impregnation with a suitable emulsion. The new softeners, plasticizers and/or tackiers of my invention are particularly valuable in compounding carcass stocks, such as tire carcasses wherein from to 35 parts by weight of carbon black per 100 parts by weight of elastomer are usually used.

The following are set forth as examples of my invention. It is to be understood that the quantities, materials, etc., set forth in the following examples, are not to unduly limit the scope of my invention.

Example I Polymerization of methylpentadiene (85 per cent 2-rnethyI-1-pentadiene and 15 per cent 4-methyl-1,3-pentadiene) was eifected at 10 C. according to the following recipe:

Parts by weight Boosters of 0.35 part hydroperoxymetluane` and 0.57 part tetraethylenepentamine were added during the run at 16.8, 40.8, and 72.7 hours, respectively. A conversion of 84.5 per cent was obtained in 117 hours. The polymer was a very soft, tacky material.

The basic recipe given above was used for the polymerization of 1,3-pentadiene (70 per cent trans-pentadiene, 20 per cent cis-pentadienaand 10 per cent other material, chiey cyclopentene) with boosters being added at 19, 43, and 67 hours,

respectively. Insteadfof0135 part dmethyl(diiso propylphenyl)hydroperoxymethane, an equivalent amount of dimethyl(tert-butylphenyl) hydroperoxymethane was used in the last two boosters. A conversion of 71.8 per cent was reached in 118 hours. This polymer was also a very soft, tacky material.y

The polypentadiene and polymethylpentadiene prepared as described above were evaluatedin a carcass recipe using a 53 Mooney, -10 C. butadiene/styrene elastomer prepared with a mixed emulsier consisting of 3.5 parts potassium rosin soap (Dresinate 214) and 1.5 parts fatty acid soap (potassium soap)., A mixture of 5.0A parts` Paraflux (an asphaltic flux) and `215 parts Staybelite resin (hydrogenated rosin: brittle solid with pale amber color and slight odor; sp. gr. 1.045; M. P., 76 C.; acid number, 162 saponication number, 167) was used as Aa control. 'I'he compounding recipe was as follows:

. Parts by weight Butadiene/styrene elastomer 100 1 A high abrasion furnace carbon black.

2 Polymerized trunethyldihydroquinoline.

3 Polymethylpentadiene polypentadiene, or a mixture of 5.0 parts. Paraux and .5 parts Staybelite resin. 1. 4 Reaction product of 'butyraldehyde and butylidene ani- The stocks were cured 30 minutes at 307 F. and physical properties determined. The following results were obtained: y

' Softener Poly- Poly- Paradux-i- Ia peut staybiite diene diene Resin Unaged samples:

Compounded Mooney, MS l l 1 31. 5 31.0 29. 5 Stressstraxn propertles at 300% Modulus, p. s. 'i.. 1,380 1,320 1, 090 Tensilap. s. 1 3,000 2, 770 3, 230 Elongatlon, percent. 4.30- 440 525 Hysteresis, AT, F 34.8 34. 4 34. 4 Resilience, percent 76. 6 77. 5 76. 2 Flex life, M 1.9 2.1 1.7 Shore hardness..-" 54 52 52 Compression set, percent..." 10.6 10. 2 12.1 Tack (meter) 320 200 40 A Oven-Aged 24 Hours at 212 F.:

Stregs-'strain properties at 300%.niodu1u s, p. s. i... 1, 980 1,980 1,650 Tensile, p. s. 1 2, 270 2, 330 2, 480 Elongation, percent 320 31 380 Hyslteresls, AT, F f.- 34. 4 34. 4 32. 7 Resillence, percent. 77. 5 79. 6 80. 0 Flex life, M 0.1 0.1 0. 3 Shore hardness 57 The stocks containing the pentadiene polymers exhlbi'ted higher modulus in bothr unaged and y agedA samples and much better tack'than the control. y

EXAMPLE II Polypentadiene and polymethylpentadiene prepared as described in Example I, were evaluated as softeners in a tread recipe using two rubber stocks, a 50-55 Mooney viscosity butadiene/- styrene elastomer prepared at 5. C. and a 53 zgsf.

Mooney -butadienestyrene eiestemer piernas-.ed 1am IIIV -10` (see Example L), .An asphalt softener A and fpoiymethylpentediene, p'pr'ed die'so'ib'd in Exemple I were evalu- Coitio ih'ea'chgease. following compounding Parts by weight 1100Y s of fand parts, respectively, of pn1yp`ent`ahalt softeners 0724.5 814+ www .4me

Softener ,Rolipentarhene The follow- The rubber stocks 'were eompeunded y.es yfollows (asphalt '#6) was lused las a control .in each cese- Paiymetnyi- .pentadiene mm .sewage 92d 311 n .een zwem rmine .mlla'rts 511mg 10 Parts g'5 Parts *umane carbon black.

properties 1 Loadings di 5 emi 1U punts, respectively, .of polypentadiene and ym'ethyllienterliene, :mtl 10 parts asphalt softener. A Tgh'a' rasir'm 1 The samples were cured 530 minutes at 307 Unaged Samples: K

Compounded Mooney, 'MS 1%: Stress-.strain 300% modnl1is, p. s. Elongaton, percent-. 'Stress-Strain properties t 200 t i Tenslle, p. s.1

arbon 'black Stcarie acid.

pol

and `,physical properties dete ing 7.resul-ts were obtained 5 C. Elestomer- 300% Modu1s,p. s. i. A Tensile, p. s, i

properties F.-

300% mod111us,-p. s. 1 .Tensllm p. s. A1 'Elongation, percent.. Hysteres'is, AT., lil. Resilience, percent. Flex life, M.

Abrnsion loss, grams 10 C. Elelstomerples: Compounded lilooney, B/IS 1%. Stressstrain propertles Ff flllrmgation, percent.

properties 200 J v Tensilenp. s. 1

Oven-aged '24 .lors et 212 F..

HStress-Strahl Shore Hardness..

Unagedem Stress-strain Elougatlon, percent Hysiteresis, AT., F

Shore hardness Abrasion loss, gremsw Compression set, percentA Extrusion, inches/minute Extrusion, grams/minute Tack, hand Oven-Aged 24 Honrsat 212 F..

4 The samples were cured at 307 F. to 20 per cent compression set and the physical properties determined. The following results were obtained.

`Stress-strain propermes '80 FF-,

300% modulus, p. s. i Tensilenp. s. i Elonga'tlou, peroen Hysteresis, AT, F Resilience, percent Flex life, M Shore hardness Abrasion loss, grams.

The 'above vdata. show that thel pentadene polymers impart higher modulus and tack than the control in both the 5 C. and 10 C. s-tockfs.

Softener Polymethylolypentadiene pentadiene Asphalt Barts Parts Parts Parts Parts .Barts Unaged Samples: l

Gompoimded: Mooney at:

212vE., MS l%. 32.5 36. .33s ,i 36.' 3B. 38 Minutes cure to 7' Com'- pressiomset 33,.' 33 I 34x 332.52 37 A 34.

Stresstrain properties at 300% Modulus, p. s. L.-. 1, 800 2, 230 1, 745 2,070 1, 4805 Tensile, pr. s. r. 2;,670 2;,830. 1 2;590. i 2;; 770 2,' 720.y

Elongation, percent 390 365 400 370 535'4 Hysteresis, 'A5139' F- i i 7.4263 79.0 75.2 77.19;r Resilience, percent... .2 59.0 58.9 59.3 58.11. Flex-life, i 0.5 1.3. l 1,9 6. 8 I Shore hardness 5S. l 60 515; y `59` 57.155 Abrasion loss, gramsl 3.10 I 2.80 4.04% v 3.12 2. 91,. Extrusion at 250 F.-

Inches/minute 40. 3 40. 4 42. 2 37. 0

Grams/minute- 100 104 102. 5 110. 5 105 Tack, immediate 5 5 4 4 4 Tack, after 24 hours 6+ 6- 4 4 3- Power, Watt hours- Mill..- 840 990 960 910 1, 100

Remill 350 330 320 350 360 Oven-Aged 24 Hours at 212 F.:

Stress-strain properties at 300% modulus, p. s. i 2, 40 2, 300 2, 200 2, 900

Tensile, p. si 2, 55o 2, 740 55o 2, 680 2, 99o 2, 97o

Elongation, percent 270 28 270 380 300 Hysteresis, A F. 64. 9 63. 5 64. 5 64. 2 62. 8 Resilience, percent... 63. 7 65. 3 63. 6 65. l 62. 5 64. 1 Flex life, M 0.8 0. 9 0.8 1. 6 4. 1 2.7 Shore hardness 65 66 64 66. 64 66 Abrasion loss, grams 1 2. 65 2. 47 3. 16 2. 68 3. 21 2. 73

1 35 minute cure.

As 1n the previous examples, the above samples liquld polymer 1s a polymer of monomethyl-LS- containing the pentadiene polymers show higher modulus and better tack than those containing the asphalt softener.

As will be evident to those skilled in the art, various modifications of this invention can be made, or followed, in the light of this disclosure and discussion, without departing from the spirit or scope of this disclosure or from the scope of the claims.

I claim:

1. The Vulcanizable composition of claim 8 wherein said viscous liquid polymer is a polymer o1 1,8-pentadiene.

2. The composition of matter of claim 8 wherein said viscous liquid polymer is a polymer of monomethyl-1,3-pentadienes.

3. The composition of claim 8 wherein said vulcanizable elastomer is a copolymer prepared by copolymerization of butadiene and styrene monomers in an emulsion system at a temperature of from 20 to 15 C., said `.butadiene being present in an amount of from 50 to 85 weight per cent of the total weight of sai-d monomers, and said viscous liquid polymer is present in an amount of from 8 to 25 parts by weight per 100 parte by weight of said vulcanizable elastomer.

4. The composition of claim 3 wherein said viscous liquid polymer' is a polymer of 1,3-pentadiene.

5. The composition of claim 8 wherein said vulcanizable elastomer is natural rubber, and said viscous liquid polymer is present in an amount of from 3 to 25 parts by weight per 100 parts by weight of said natural rubber.

6. The process of claim 9 wherein said Viscous liquid polymer is a polymer of 1,3-pentadiene added in an amount of from 3 to 25 parts by weight per 100 parts by weight of said vulcanizable elastomer.

'7. The process of claim 9 wherein said viscous pentadienes added in an amount of from 3 to 25 parts by weight per parts by weight of said Vulcanizable elastomer.

8. A rubber-like, sulfur Vulcanizable composition comprising, a rubber-like Vulcanizable organic elastomer selected from the group consisting of natural rubber and synthetic polymers of conjugated diolefins; and a viscous liquid polymer prepared from monomers consisting of pentadienes of the formula where X1 is selected from the group consisting of hydrogen and a methyl radical, X2 is selected from the group consisting of hydrogen and a methyl radical and X3 is selected from the group consisting of hydrogen and a. methyl radical.

10. A rubber-like, sulfur rubber-like vulcanizable composition comprising, a vulcanizable organic elastomerl selected from the group consisting of natural rubber and synthetic polymers of -11 conjugated diolens; and a viscous unmodified liquid polymer prepared from monomers consisting of pentadienes of the formula from the group consisting of natural rubber and l5 synthetic polymers of conjugated dioleflns to produce elastomer products, that improvement which comprises adding to said rubber-like Vulcanizable organic elastomer as a plasticizer a 12 liquid Viscous unmodified liquid polymer prepared from monomers consisting of pentadienes of the :formula where X1 is selected from the group consisting of hydrogen and a methyl radical, X2 is selected 10 from the group consisting of hydrogen and a methyl radical and X3 is selected from the group consisting of hydrogen and a methyl radical. WILLARD M. ST. JOHN, JR.

References Cited in the le of this patent UNITED STATES PATENTS Name Date Gessler Sept. 5, 1950 Number 

8. A RUBBER-LIKE, SULFUR VULCANIZABLE COMPOSITION COMPRISING, A RUBBER-LIKE VULCANIZABLE ORGANIC ELASTOMER SELECTED FROM THE GROUP CONSISTING OF NATURAL RUBBER AND SYNTHETIC POLYMERS OF CONJUGATED DIOLEFINS; AND A VISCOUS LIQUID POLYMER PREPARED FROM MONOMERS CONSISTING OF PENTADIENES OF THE FORMULA 